This invention relates to the field of collapsible shipping containers.
While many inventors have in the past devised reusable shipping containers that collapse into a smaller volume for return shipment when empty, such containers have had several disadvantages. One such disadvantage was the use of complex and expensive latch devices such as disclosed in U.S. Pat. Nos. 1,176,332; 908,988; 1,004,414; 1,307,757; 2,720,998; 3,107,023 and 3,414,156. Attempts to provide quick operating latches to increase the speed with which the container may have been assembled or disassembled include U.S. Pat. Nos. 1,156,673 and 3,542,234. In U.S. Pat. No. 2,517,178 a latch means was disclosed which was resiliently deformable to hold the sides in the upright position, but in that arrangement gaps were required adjacent the bottom member of the container to enable the pivoting collapse of the container walls. In addition, U.S. Pat. Nos. 3,360,180 and 3,446,415 disclose collapsible containers having resiliently deformable latch means which require gaps in the side walls to enable pivoting erection and latching of the walls. These gaps or openings permitted entrance of dirt and other undesirable matter into the containers and the latches provided numerous crevices which were exceedingly difficult to clean and sterilize and therefore these containers were not suitable for the transportation of processed foods and other items of similar nature.
Sealable collapsible containers, such as those disclosed in U.S. Pat. Nos. 3,542,234 and 3,809,278, have been known, but required special seal elements which require additional maintenance and the containers were of such larger size as to be unwieldy and very difficult to sterilize. Further, the collapsible shipping containers disclosed in U.S. Pat. No. 3,809,278 have non-integral side walls which must be attached to a base member requiring additional special seal elements.
Several collapsible containers having side walls integrally attached to a base member have been known, such as those disclosed in U.S. Pat. Nos. 3,349,289; 3,330,437; 3,207,357; and 2,720,998. However, such containers required special latch means, mentioned hereinbefore, and were incapable of being vertically stacked in a nesting arrangement in both the collapsed position and the erect position without the probability of inadvertent movement during shipment. U.S. Pat. Nos. 3,133,662 and 2,944,695 disclose containers having raised lid portions and base members having recesses adapted for receiving the raised lid portion of another container to prevent inadvertent movement when the containers are vertically stacked. However, those containers are not of the collapsible type and require excessive space when shipped back to the point of origin.